[Xen-changelog] Fix get_pte_flags/put_pte_flags macros. Limit 32-bit PAE to 44-bit

[BitKeeper Bot <riel@xxxxxxxxxxx>]

ChangeSet 1.1615.1.3, 2005/05/31 18:07:56+01:00, kaf24@xxxxxxxxxxxxxxxxxxxx

        Fix get_pte_flags/put_pte_flags macros. Limit 32-bit PAE to 44-bit
        physical addresses (maximum PFN that will fit in a 32-bit word).
        Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>



 x86_32/page-2level.h |    7 +++++++
 x86_32/page-3level.h |   20 +++++++++++++++++---
 x86_64/page.h        |   16 ++++++++++++----
 3 files changed, 36 insertions(+), 7 deletions(-)


diff -Nru a/xen/include/asm-x86/x86_32/page-2level.h 
b/xen/include/asm-x86/x86_32/page-2level.h
--- a/xen/include/asm-x86/x86_32/page-2level.h  2005-05-31 14:03:36 -04:00
+++ b/xen/include/asm-x86/x86_32/page-2level.h  2005-05-31 14:03:36 -04:00
@@ -40,6 +40,13 @@
 #define is_guest_l1_slot(_s)    (1)
 #define is_guest_l2_slot(_t,_s) ((_s) < L2_PAGETABLE_FIRST_XEN_SLOT)
 
+/*
+ * PTE pfn and flags:
+ *  20-bit pfn   = (pte[31:12])
+ *  12-bit flags = (pte[11:0])
+ */
+
+/* Extract flags into 12-bit integer, or turn 12-bit flags into a pte mask. */
 #define get_pte_flags(x) ((int)(x) & 0xFFF)
 #define put_pte_flags(x) ((intpte_t)(x))
 
diff -Nru a/xen/include/asm-x86/x86_32/page-3level.h 
b/xen/include/asm-x86/x86_32/page-3level.h
--- a/xen/include/asm-x86/x86_32/page-3level.h  2005-05-31 14:03:36 -04:00
+++ b/xen/include/asm-x86/x86_32/page-3level.h  2005-05-31 14:03:36 -04:00
@@ -13,7 +13,14 @@
 #define L3_PAGETABLE_ENTRIES    4
 #define ROOT_PAGETABLE_ENTRIES  L3_PAGETABLE_ENTRIES
 
-#define PADDR_BITS              52
+/*
+ * Architecturally, physical addresses may be up to 52 bits. However, the
+ * page-frame number (pfn) of a 52-bit address will not fit into a 32-bit
+ * word. Instead we treat bits 44-51 of a pte as flag bits which are never
+ * allowed to be set by a guest kernel. This 'limits' us to addressing 16TB
+ * of physical memory on a 32-bit PAE system.
+ */
+#define PADDR_BITS              44
 #define PADDR_MASK              ((1ULL << PADDR_BITS)-1)
 
 #ifndef __ASSEMBLY__
@@ -46,8 +53,15 @@
      ((_s) < (L2_PAGETABLE_FIRST_XEN_SLOT & (L2_PAGETABLE_ENTRIES-1))))
 #define is_guest_l3_slot(_s)    (1)
 
-#define get_pte_flags(x) ((int)((x) >> 40) | ((int)(x) & 0xFFF))
-#define put_pte_flags(x) ((((intpte_t)((x) & ~0xFFF)) << 40) | ((x) & 0xFFF))
+/*
+ * PTE pfn and flags:
+ *  32-bit pfn   = (pte[43:12])
+ *  32-bit flags = (pte[63:44],pte[11:0])
+ */
+
+/* Extract flags into 32-bit integer, or turn 32-bit flags into a pte mask. */
+#define get_pte_flags(x) (((int)((x) >> 32) & ~0xFFF) | ((int)(x) & 0xFFF))
+#define put_pte_flags(x) (((intpte_t)((x) & ~0xFFF) << 40) | ((x) & 0xFFF))
 
 #define L1_DISALLOW_MASK (0xFFFFF180U & ~_PAGE_NX) /* PAT/GLOBAL */
 #define L2_DISALLOW_MASK (0xFFFFF180U & ~_PAGE_NX) /* PSE/GLOBAL */
diff -Nru a/xen/include/asm-x86/x86_64/page.h 
b/xen/include/asm-x86/x86_64/page.h
--- a/xen/include/asm-x86/x86_64/page.h 2005-05-31 14:03:36 -04:00
+++ b/xen/include/asm-x86/x86_64/page.h 2005-05-31 14:03:36 -04:00
@@ -18,7 +18,7 @@
 
 #define __PAGE_OFFSET           (0xFFFF830000000000)
 
-/* These are page-table limitations. Current CPUs support only 40-bit phys. */
+/* These are architectural limits. Current CPUs support only 40-bit phys. */
 #define PADDR_BITS              52
 #define VADDR_BITS              48
 #define PADDR_MASK              ((1UL << PADDR_BITS)-1)
@@ -58,10 +58,18 @@
 #define root_create_phys          l4e_create_phys
 #define PGT_root_page_table PGT_l4_page_table
 
-#define get_pte_flags(x) ((int)((x) >> 40) | ((int)(x) & 0xFFF))
-#define put_pte_flags(x) ((((intpte_t)((x) & ~0xFFF)) << 40) | ((x) & 0xFFF))
+/*
+ * PTE pfn and flags:
+ *  40-bit pfn   = (pte[51:12])
+ *  24-bit flags = (pte[63:52],pte[11:0])
+ */
+
+/* Extract flags into 24-bit integer, or turn 24-bit flags into a pte mask. */
+#define get_pte_flags(x) (((int)((x) >> 40) & ~0xFFF) | ((int)(x) & 0xFFF))
+#define put_pte_flags(x) (((intpte_t)((x) & ~0xFFF) << 40) | ((x) & 0xFFF))
 
-#define _PAGE_NX                (cpu_has_nx ? (1U<<23) : 0U)
+/* Bit 23 of a 24-bit flag mask. This corresponds to bit 63 of a pte.*/
+#define _PAGE_NX (cpu_has_nx ? (1U<<23) : 0U)
 
 #define L1_DISALLOW_MASK (0xFFFFF180U & ~_PAGE_NX) /* PAT/GLOBAL */
 #define L2_DISALLOW_MASK (0xFFFFF180U & ~_PAGE_NX) /* PSE/GLOBAL */

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